Brominated Flame Retardants (PBDEs) in Northwest Atlantic Harbor Seals (2008)
Abstract
Polybrominated diphenyl ethers (PBDEs) were analyzed in blubber of harbor seals (Phoca vitulina concolor) collected between 1991 and 2005 along the northwest Atlantic. ƩPBDE concentrations (mono- to hexa-BDEs) detected in blubber samples (n=42) ranged from 80 to 25720 ng/g, lw, (overall mean 2403 ± 5406 ng/g lw). By age, mean ƩPBDE concentrations were: 3645±7388, 2945±5995, 1385±1265, and 326±193 ng/g, lw in pups, yearlings, adult males, and adult females, respectively. Unlike the trend for PCBs, no decreasing gradient from urban to rural/remote areas was observed for PBDEs in these samples, likely reflecting inputs from local sources. No significant temporal trend was observed for PBDEs in harbor seals between 1991 and 2005, although congener profiles shifted over time. Tetra-BDE-47 was the dominant congener, followed by BDEs-99, -100, -153, -154, and -155 in varying order, suggesting exposure to the penta-BDE product. In adult males, the hexa-BDEs contributed more to the total (22%) than BDEs-99 and -100 (14%), and concentrations of BDE-155 were elevated compared with -154. Higher BDEs were detected in a subset of seals (n=12) including hepta-BDE-183, the marker for the octa-BDE mixture, and octa-BDE 197, along with several unidentified hepta- and octa- congeners. BDE 209 was detected in seal blubber at concentrations ranging from 1.1 to 8 ng/g, lw, indicating that deca-BDE is bioavailable in this marine food web. This is the first study to document the accumulation of BDE-209 at measurable levels in wild harbor seals. While the PBDE patterns in blubber indicate exposure to all three BDE commercial mixtures, the data also suggest that BDE-209 debromination by seal prey fish may contribute to the loading of lower brominated congeners (hexa- to octa-BDEs) in these seals.
Shaw et al. (2008) Chemosphere 73: 1773-1780.
Background
This is the first study to report the occurrence of the brominated flame retardants PBDEs in pinnipeds from the northwest Atlantic marine region. The levels of PBDEs in these seals are among the highest in the world, reflecting the high market demand for flame retardants in the US over the past 40 years. These compounds leach out of consumer products such as furniture foam, textiles, electronics, and plastic casings for TVs and computers and are found at high levels in dust in homes and offices. PBDEs enter estuarine and coastal food webs from diffuse sources including households, industries, wastewater treatment plants and landfills.
Of the three commercial PBDE mixtures, the global market for the Penta-BDE formulation was dominated by North America for more than three decades. The Penta- and Octa-BDE formulations were banned from use in Europe in 2004 and both products were subsequently withdrawn from the US market. The third commercial product, Deca-BDE (>97% BDE-209), has only recently begun to be regulated in Europe and the US. Deca-BDE is strongly particle associated and marine sediments constitute a vast reservoir for ongoing exposure to BDE-209 in marine food webs. In addition to direct exposure to commercial PBDE mixtures, there is concern that metabolic debromination of Deca-BDE may contribute to the loading of less brominated, more persistent and toxic BDEs in marine biota. Whereas earlier studies have rarely measured the fully brominated Deca-BDE (BDE-209) in marine mammals, this study measured BDE-209 and other highly brominated BDEs in harbor seal blubber samples.
Findings
Total PBDE levels in these seals are an order of magnitude higher than those in seals from other marine regions, reflecting the high-volume use of penta-BDE in North America. Levels of total PBDEs in the younger seals (3-4,000 ng/g, lipid) are among the highest reported in the world. The predominant BDE pattern (BDE-47, -99, and -100) in seal blubber indicates exposure to the Penta-BDE commercial mixture. The congener pattern in these seals also provides evidence that the Octa- and Deca-BDE products have contaminated this marine food web. This is the first study to detect Deca-BDE (209) above trace levels in a marine mammal species. BDE-209 was present at low but measurable levels (1-8 ng/g, lipid) in harbor seal blubber. This finding is significant as it provides evidence that deca-BDE is bioavailable and is transferred through the marine chain. The potential for BDE-209 to accumulate in high trophic level marine species is relevant to policy decisions, as the production and use of Deca-BDE has only begun to be restricted worldwide. Although the toxic effects of PBDEs in marine mammals are not known, possible immune- and endocrine (thyroid)-disrupting effects have been suggested by recent studies. Harbor seals along the northwest Atlantic suffer from recurring die-offs and disease; thus continuing inputs of Deca-BDE to this marine food web are of concern.
Publications resulting from this research: (* pdfs available)
Shaw, S. D., Brenner, D., Berger, M. L., Fang, F., Hong, C.-S., Addink, R., Hilker, D. (2008). Bioaccumulation of polybrominated diphenyl ethers in harbor seals from the northwest Atlantic. Chemosphere 73: 1773-1780.
*Shaw, S.D., Brenner, D., Berger, M.L., Fang, F., Hong, C-S., Storm, R., Hilker, D., O'Keefe, P. (2007). Polybrominated diphenyl ethers (PBDEs) in harbor seals from the northwestern Atlantic. Are seals debrominating DecaBDE? Organohalogen Compounds 69:829-832.
*Shaw, S.D., Berger, M.L., Brenner, D., Fang, F., Hong, C-S., Storm, R., O'Keefe, P. (2006).
Polybrominated diphenyl ethers (PBDEs) in harbor seals (Phoca vitulina concolor) from the northwestern Atlantic. Organohalogen Compounds 68: 600-603.
*Shaw, S.D. (2006). Seals as Sentinels: Assessing Toxic Contaminants in Northwestern Atlantic Coast Seals. Final Project Report to the National Oceanographic and Atmospheric Administration. Marine Environmental Research Institute, Blue Hill, ME, 123 pp. Contract No. EA133F05CN1358.
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